The GEPON is the standard of a passive optical communication network PON that has been standardized as IEEE 802.3ah in the Electrical and Electric Society in U.S. As one structural example that realizes the above standard, up to now, there has been disclosed an optical receiving apparatus that controls the changeover of a transimpedance by using a level detector and a delayer as a changeover system that changes over the transimpedance of the preamplifier by means of a switch (for example, refer to JP-A No. 2005-86466).
Also, as one of the burst optical receivers that are the optical receivers which are applied to the optical communication network and transmit a signal beam in a burst form, up to now, there has been the following burst optical receiver. That is, the burst optical receiver includes a mask generator circuit that changes over an amplification gain according to the intensity of an electric signal that has been converted from a received signal beam, turns off a control signal when the rising and falling change points of the electric signal that has been subjected to amplification reach a given count value, and suppresses a process of generating an H level signal with respect to a first bit of the signal cell. There is disclosed a structure in which when N bits are required for changing over the gain of the burst preamplifier, the mask generator circuit sets a control signal to an on-state for an N-bit receiving time period before the gain changes over after a reset pulse signal has been input to the mask generator circuit (for example, refer to JP-A No. 2004-180176).
Also, as a receiver circuit in a burst multiplex transmission system, more particularly, a burst signal detector circuit that detects the arrival of the burst signal, up to now, there has been a technique by which after a counter circuit inputs the burst signals and completes the counting of a given number of pulses, an output signal from the counter circuit is changed to a high level to detect the burst signal (for example, refer to JP-A No. 06(1994)-318908).